Weak ferromagnetism in La-doped BiFeO3 multiferroic thin films

Abstract

Bi 1Àx La x FeO 3 thin films (x ¼ 0.0, 0.3, 0.5) were grown on glass substrates by thermal physical vapor deposition. The monoclinically distorted crystal structure of the films was revealed by x-ray diffraction at room temperature. Field and temperature (up to 1000 K) dependences of magnetization were studied. Saturation of the room temperature magnetic hysteresis loop has been observed at magnetic field above 0.15 T, demonstrating the weak ferromagnetic nature of the thin films. Our magnetic force microscopy results show clearly the presence of magnetic domains in BFO thin films. These structural and magnetic properties suggest the absence of magnetic spiral spin structure in monoclinically distorted BFO-based thin films. V

Enhanced ferroelectric polarization and magnetization in BiFe1−xScxO3 ceramics

“…Although our maximum P r is smaller than the reported largest value among the doped BFO (31 mC/cm 2 for BiFe 0.9 Dy 0.1 O 3 ceramics [11]), but still much larger than those of most doped BFO ceramics reported [9,10,[12][13][14][15][16][17][18]. It is generally considered that structural distortion plays an important role in improving the polarization in doped BFO system [21].…”

“…In addition, the magnetism in pure BFO is rather weak, which also hampers its applications in multiferroic devices. To improve the ferroelectric and ferromagnetic properties in BFO ceramics, one reasonable idea is to introduce ion dopant (such as Dy 3+ , La 3+ , Ca 3+ /Sc 3+ , Ti 4+ , Mn 4+ ) into the A-or/and B-sites of BFO [9][10][11][12][13][14][15][16][17][18]. For examples, Zhang et al [11] reported saturated ferroelectric polarization in Dy-substituted BFO ceramics at room temperature with a large remnant polarization of 31 mC/cm 2 .…”

“…Although the spontaneous polarization (P s ) of up to 100 mC/cm 2 has been reported in BFO epitaxial films and single crystals, excellent ferroelectricity is rarely observed in BFO ceramics deteriorated by their large leakage current from some complicated reasons, e.g., second phases, charge defects and nonstoichiometry [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In addition, the magnetism in pure BFO is rather weak, which also hampers its applications in multiferroic devices.…”

Magnetodielectric coupling in epitaxial Nd2CoMnO6 thin films with double perovskite structure

“…5(c) shows that magnetic susceptibility obeys the Curie-Weiss law Weiss constant, H ¼ þ151 K, also indicates that the interaction between Co 2þ and Mn 4þ is ferromagnetic type. The measured saturation magnetization at 5 K is 1.04 l B /unit cell, which is smaller compared to bulk due to the epitaxial strain 19 developed during deposition and antisite disorder of the Co 2þ and Mn 4þ ions. 18,20 The bifurcation between ZFC and FC is apparent at an irreversible temperature (T irr ), which is the temperature value at which the irreversible magnetic moment, defined as Dm ¼ m FC À m ZFC , becomes different from zero, indicating the onset of a freezing process.…”

Enhanced multiferroic properties in epitaxial Yb-doped BiFeO3 thin films

“…[11,17,18] Various attempts have been made to enhance the properties of BiFeO 3 in device applications. The doping of BiFeO 3 with transition metals [18][19][20][21] or rare-earth ions [22][23][24][25] improves both the ferroelectric and ferromagnetic properties. Recently, doping of BiFeO 3 with Ho [26] or Ce [27] has proven to improve the ferroelectric properties of the BiFeO 3 films.…”